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SUMMARY:Adaptive Hybrid Density Functionals - Dr Alastair Price\, Universi
 ty of Toronto
DTSTART:20240529T133000Z
DTEND:20240529T143000Z
UID:TALK215404@talks.cam.ac.uk
CONTACT:Lisa Masters
DESCRIPTION:In this work we explore how the contributions of exact exchang
 e significantly impact electronic states\, which are key in forming and br
 eaking covalent bonds in chemical species. Traditionally\, hybrid density 
 functional approximations have been effective by averaging the exact excha
 nge admixture across various compositions. However\, they've struggled to 
 achieve high-level quantum chemistry accuracy due to delocalization errors
 .\n\nTo address this\, we introduce a novel approach to dynamically adjust
  hybrid functionals by generating optimal admixture ratios of exact exchan
 ge for any given chemical compound. This is achieved using highly data-eff
 icient quantum machine learning models with minimal computational overhead
 .\n\nOur adaptive Perdew-Burke-Ernzerhof based hybrid density functional (
 aPBE0) demonstrates remarkable accuracy in calculating atomization energie
 s. Additionally\, aPBE0 enhances the energetics\, electron densities\, and
  HOMO-LUMO gaps in organic molecules from the QM9 and QM7b datasets. We've
  also used aPBE0 with a large basis set to revise the entire QM9 dataset\,
  resulting in more accurate quantum properties\, including stronger covale
 nt binding\, larger band gaps\, more localized electron densities\, and gr
 eater dipole moments. While aPBE0 performs exceptionally well in equilibri
 um conditions\, it does face limitations in accurately dissociating covale
 nt bonds beyond the Coulson-Fisher point.
LOCATION:Unilever Lecture Theatre\,  Department of Chemistry
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